Gelatin dynamite composition



Patented Feb. 26, .1935

1,992,189 eata'rm nxrremrn eoosrrrom' Fred r. Chapman, Wilmington,

E. I. du Pont de Nemours & mington, Bet,

Bet, assignor to Company, Wila corporation of Delaware No Drawing.Application June 24,

- Serial No. 619,126

9 Claims. (CI. 52-13) This invention relates, in general, to gelatindynamites having improved explosive properties and, more particularly,to gelatin dynamites which exhibit superior sensitiveness and propa- 5gating properties after long periods of storage mally liquid explosiveingredients. Some form and under adverse conditions of use.

The class of high explosives usually termed gelatin dynamites ischaracterized by the fact that at least one ofthe ingredients is solublein, and greatly increases thevisoosity of, the norof nitrocellulose,preferably nitrocotton, is ordinarily used as the gelatinizing material,and this is mixed with nitroglycerin, nitroglycol, and the like, or withmixtures of similar nitrated aliphatic alcohols with nitrated aromatichydrocarbons suchas trinitrotoluene or dinitrotoluene in the properproportions to produce a viscous, plastic, and cohesive mass. Explosiveproperties such as strength and gaseous products of combustion' aremodified and adjusted by addition of suitable oxidizing agents andcarbonaceous combustibles to the above-mentioned plastic mass.

By the term gelatin dynamites, as referred to herein, is meant thoseexplosives which contain a relatively high proportion, by volume, ofgelatinized liquid explosive and are usually cartridged by an extrusionprocess. These are differentiated from the class of high explosivesknown as semi-gelatins, by the fact that the latter contain arelativelylow proportion, by volume, of gelatinized liquid explosive and are notadapted to' cartridging by the existing extrusion processes.

The usual commercial gelatin dynamites vary in grade strength, from 20%to 90%, depending upon the explosive content. These grades also vary indensity, for example, from 1.70 for the low grades to-as low as 1.60 forthe grades, and even lower than this-figure for the grade.

The sensitiveness, or propagating power of gelatin dynamites variesnotably, depending on the composition and grade, and also to a markeddegree on the density of the explosive; the higher the density, thelower the propagating power, other things being equal. The propagatingpower of gelatin dynamites decreases with age because of a gradualincrease in density,-this increase being due to theloss of small airbubbles entrapped in the gelatins at the time of manufacture.Furthermore, in deep oil wells and in submarine blasting, where theexplosive is subjected to considerable external pressure, the

density of the gelatin explosive is increased and its propagating powermaterially decreased.

It is quite common in the case of relatively deep submarine blasting,for thegelatin to be so adversely affected by the water pressure that itfails to propagate completely, or that a portion of the charge burns,thereby failing to properly blast the rock, thus making it necessary tore-shoot after the dredge has cleaned up the area blasted.

This invention has as an object the production of gelatin dynamiteshaving substantially lower initial densities than have heretofore beenpracticable. A further object is the production of gelatin dynamiteswhich will maintain low densities and satisfactory sensitiveness andpropagating power, over long periods of time, under either atmosphericor greater than atmospheric pressures, and dynamites which are superiorto gelatins heretofore manufactured for use in oil or gas well, and ingeneral submarine blasting. Other objects will appear as the inventionis further described.

I have found that these objects may be accomplished by the use of lowdensity vegetable piths, in place of wood flour, starch, ivory nut meal,or the like, which comprise the carbonaceous combustibles now mostcommonly used.

My invention comprises,'broadly, the use in gelatin dynamite of lowdensity vegetable piths.

By the term vegetable piths is meant the product obtained by separationof the pithy portion of suitable plants from the outer covering of highdensity material.

I have found, for example, that the pith of sugar cane (commonly termedbagasse pith) constitutes a very desirable material for the purposes oimy invention. Bagasse pith is usually obtained from sugar cane, afterextraction of the sugar, by screening out the major portion of the longfibers, leaving substantially pure pith.

Small percentages of the fibers are not objectionable and do notinterfere with securingthe desired results, but the pith as used in myinvention should preferably not contain over 25% of fiber. Other methodsof separating pith from fiber such as, for example elutriation byameansof air or water, are well known in the art and may be utilized inobtaining bagasse pith of properties which .are satisfactory for use inmy invention.

The product obtained by any of the above mentioned processes consistsimia very finely divided material having a distinctly cellularstructure. By certain modifications in the preparation of v thesubsequent This material may be prepared by the following method. Thecorn stalks, preferably welldried in advance, may be stripped of theirleaves and distintegrated by rasping, for example, against a metallicwheel containing relatively small teeth on its periphery. The finelydivided material thus obtained may be passed through a screen, forexample, one containing six meshes per linear inch.

Various amounts of relatively high density fibrous material may bepresent in corn stalk pith prepared by the method described in theforegoing. While not essential, it may be desirable to remove asubstantial proportion of the fibrous material. This may be accomplishedby any one of several processes well known in the art, for example, byan elutriation process, preferably using air as the classifying medium.

While I have found that all pithy materials, similar to those describedin the foregoing, are relatively low in density, I prefer to use thosewhich, in' the form of particles passing a sixmesh screen, have adensity between 0.1 and 0.3, preferably less than 0.2. It should bementioned that the densities referred to are those obtained while thematerial is under 25 pounds per square inch pressure. Although only twotypes of vegetable pith have been described, it will now be apparentthat various equivalent materials for my' purpose are available whichmay be used without departure from the spirit of my invention. Asexamples, I various varieties of sunflower stalks, including Jerusalemartichokes, etc.

In order to obtain lower densities than those occurring in the naturalproduct, I may use one of the several treating processes which are wellknown in the art. Described briefly, such a treating process may consistin steaming the pith with a sbstantial proportion of water, whereby thecellular structure is expanded and a lowering in density results. Afurther treating process, which may find use in the prepara-. tion ofvegetable piths for use according to my invention, consists in-treatingwith high external and internal pressures with sudden release of saidpressures. This process results in a substantial expansion of thecellular structure with consequent lowering in density.-

While not essential, it is preferable that all of the materialsdescribed in the foregoing should be dried to a reasonable moisturecontent before use.

My invention is applicable to all types of gelatin dynamites. The threemain classes of the gelatin dynamites are commonly known as straightgelatins, ammonia gelatins, and permissible gelatins. The straightgelatins range in strength, according to the usual terminology, from 20%to 100%. The latter is commonly known as blasting gelatin. Straightgelatins ordinarily contain a gelatinized liquid explosive ingredient,with varyingproportions of sodium nitrate and carbonaceous combustibles,depending cite the pith of corn cobs,

the pithy materialon the strength and other properties which may berequired.

The ammonia gelatins usually contain a smaller proportion of gelatinizedliquid explosive than grade strength, the

straight gelatins of the. same strength being made up by the use ofammonium nitrate. Permissible gelatins may be of either the straight orthe ammonia type, with the addition of a safety ingredient which permitstheir safe use in coal mines where there is danger of explosion frommine gas or coal dust.

While my invention is applicable to many different forms-of gelatindynamite, the following examples are given to illustrate itsapplicability to each of the commontypes of gelatin dynamite compositiondescribed in the foregoing.

Type gelatin ingredient Straight Ammonia Permissible Per ce'n Per centPer cent N itroglycerin 50. 60. 0 30. Dinitroto1uene. 3. 2.Nitrocott0n.- 2. 6 2. 3 0. Sodium nitrate 36. 6 2. 2 44. Ammonium nitrat24.0 Ammonium chloride 15.0 Vegetable pith. 4 0 6.0 2.0 Star 5 l 1.0 4.5 Chalk l 7 1.0 1.0

As illustrative of the .value of my invention,

there is given below a comparison of the formulas and properties of astandard 60% straight gelatin (A) with those of a representative 60%straight gelatin (B), containing one of my low density vegetablepithproducts. It will also be seen from the following table that agreatly improved product in this class of explosives is obtained whichnot only has a higher sensitive-- 'ness at the time of manufacture butretains these properties during storage.

Nitroglycerin 50.0 50. Nitroc n 2. 6 2. Sodium nitrate 36. 6 36. Woodpulp (dens.-0.247) 7.0 Bagasse pith (dens.-0.165) 4. Star l. 6 4. Ivorynut meal 0. 5 1.

alkl. 7 1. Cartridges 96 101 Density after 1 day's storage 1.601 1.538Density after 1 months storage at 100 1. 662 l. 566 Sensitiveness after1 day's storage 10' Sensitiveness after 1 month's storage at 100 F- 3'15' It is apparent that the extent of the density decreases, which maybe obtained through the use of low density vegetable piths, willbelargely dependent on the' amount of such material it is desirable touse. From a practical standpoint, however, the amounts are limited bythe extrudability of the gelatin and the undesirable effects onproperties involved in the use of too high percentages of carbonaceouscombustibles. Preferably, I use between 0.5% and 15% of the low densityvegetable piths, although my invention contemplates the use of between2% and 10% of these materials as most satisfactory.

It would ordinarily be expected that the incorporation of thesevegetable piths and like materials in gelatins would result in a productthat would stiffen, or harden, particularly upon storage. On thecontrary, the process of manufacture of the gelatin type of dynamite isnot only improved, for the .reason that the incorporation of thesematerials in gelatins results in a product that is more easily worked inthe various steps of the process, particularly in the extruding,cartridging and packing operations, but the finished product can beshipped into and stored in hot climates without the loss 01 plasticityof the product.

It-will be understood, of course, that the percentage of ingredientsgiven in the foregoing examples may be varied within wide limits, andthat additional ingredients may be introduced without departure from thespirit of my invention. It is also to be understood that I do not limitmyself to the use of vegetable pith as the sole combustible material,either high or low density, inasmuch as certain properties of othercombustibles may cause their use to be of advantage. I may also use inplace of all or part of the nitroglycerin, for example, nitroglycol,nitrated polymerized glycerin, nitrated sugars, nitrated aromatichydrocarbons, etc.

It will be apparent from the foregoing that many variations of myinvention exist and may be practiced within the scope thereof and forthis reason I do not intend to be limited except as indicated in thefollowing pater t claims:

I claim:

1. A low density gelatin dynamite comprising a gelatinized liquidexplosive and a vegetable pith. 2. A low density gelatin dynamitecomprising a gelatinizecl liquid explosive and bagasse pith.

3. A gelatin dynamite comprising a gelatinlzed liquid explosive and thepith of corn stalks.

4. A gelatin dynamite comprising a gelatinized liquid explosive and thepith of sunflower stalks.

5. A gelatin dynamite comprising a gelatinized liquid explosive and thepith of sunflower stalks of the variety known as Jerusalem artichokes.

6. A gelatin dynamite comprising as ingredients a gelatinized liquidexplosive and a vegetable pith ,which, in the form of particles passinga G-mesh screen; has a density not greater than 0.3.

' 7. A low density gelatin dynamite comprising a, liquid explosiveingredient, nitrocellulose, and from 0.5% to 15% of a vegetable pith.

8. A gelatin dynamite, characterized by its relatively low density,nitroglycerin, nitrocotton, and bagasse pith, said. bagasse pith havinga density between 0.1 and 0.3.

9. A gelatin dynamite, characterized by its relatively low density,containing as ingredients nitroglycerin, nitrocotton, one or moreinorganic oxidizing materials, carbonaceous combustible materials, andbagasse pith in the amount 'of 0.5% to 15%.

containing as ingredients

